/Engine/Source/Runtime/Datasmith/DatasmithCore/Public/IDatasmithSceneElements.h
Get the ith composite texture inside this composite used as layer mask
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [IDatasmithCompositeTexture](API\Runtime\DatasmithCore\IDatasmithCompositeTexture) > & GetParamMaskSubComposite ( int32 i )